During a typical workday, depending on the task being performed, a seated person will tend to seek to sit upright, to lean forward, to lean backward, and to lean to the side. Therefore, it would be desirable to have a chair capable of providing complete and proper ergonomic support while the chair is moved through positions that correspond to various tasks that a sitting person might be called upon to perform. It would be similarly desirable to provide a chair that can be readily raised or lowered for height adjustment.
Still further, since people of the same height will vary in, for instance, the length of the upper legbone from the hip to the knee, it would be desirable to have a chair capable of accommodating such variations. It will be further appreciated that a chair providing ergonomic support must accommodate not only different lengths of the upper leg, it must also be responsive to the changing curvature of the spine as a person leans forward or backward. For example, when a person leans backward, the lumbar portion of the spine moves forward relative to the rest of the spine. Accommodating such changes would enhance the comfort, posture, and, potentially, the physiological health of the user.